Pneumatic and like tool



Aug- 7, 1934- J. 'ARTHUR 1,969,539

PNEUMATIC AND LIKE TOOL Filed Oct. 7. 1952 3 Sheets-Sheet l INVENTW Aug.7, 1934. ARTHUR 1,969,539

PNEUMATIC AND LIKE TOOL Filed Oct. 7. 1952 s sheets-sheet 2 7, 1,934. J.ARTHUR PNEUMATIC AND LIKE TOOL Filed-Oct. 7, 1932 3 Sheets-Sheet 3Patented Aug. 7, 1934 PNEUMATIC AND Like 'r'oon I John Arthur, Camborne;England, assignor to Holman Brothers Limited, Camborne, England,

a British company.

Application October 7, 1932, Serial N0. 636,61 9 i I Y InGreat BritainJanuary 13, 1932 10 Claims. (o1.'121-' 19) This invention consists ofimprovements in or relating to pneumatic and like tools.

Fluid-driven tools (such as pneumatic hammers) have already beenproposed having a working cylinder, a free piston therein, a plate ordisc valve for controlling admission of driving fluid alternately toopposite ends of the cylinder, and one or more exhaust ports to becovered and uncovered by the piston; and in this specification theexpression a fluid-driven tool of the type described is intended tocover such tools.

An object of my invention is to ensure inva fluid-driven tool of thetype described that excess fluid pressure detrimental to the operationof the tool is not built up in front of the piston during its travel inone or the other direction, and to this end the invention provides afluiddriven tool of the type described with fluid distributingmeans'comprising in combination a main valve having two faces opening toopposite ends of the cylinder, an annular auxiliary beat valve and valvecasing wherein said auxiliary valve is axially movable, two fluid pas-'sages which lead from one and the same face ,of the auxiliary valve toone end of the cylinder and to exhaust respectively, and a thirdfluidpassage leading from the other face of the auxiliary valve to thatface of the main valve which also opens to the same one end of thecylinder. A further object of the. invention is to-:ensure in theconstruction of fluid-driven tool described in the foregoing paragraphthe delivery of an uncushioned blow by the piston when making itsforward or' striking stroke, and the two fluidpassages which lead fromone and thesarne face of theauxiliary valve are then arranged topass ofthe cylinder, that passage passing to the forward end of the cylinderbeing joined by a further fluid-passage having branched fluid-passagesleadingto the opposite face of the auxiliary valve and one-face of themain-valverespectively.

It is an alternative object. of the invention when the tool is such thatthe piston stroke is substantially in excess of the length of the pistonto ensure full travel of the piston on its sages leading from one andthe same face of the auxiliary valve then pass respectively to exat apoint in the length thereof distant from the actual rearmost point to anextent which is less than the length of the piston, while a thirdfluid-passage passes from the other face of the cylinder and the mainvalve. The main and embodying thisinivention; respectively to exhaustand to the forward end 1 {valve end taken on aidifferent plane fromFigure 1; 1 ,1

'upof pressure behind the piston on its return haust andto the rearwardend of the cylinder f auxiliary valve-and joins; the fluid-passage leadingvfrom one face of the main valve to they-rear,- ward end of thecylinder.

v It is also an object of the invention toredu ce -vibration in; toolsof the typedescribed an d'par- ,ticularly ,to reduce vibrationorrfluttering of the main valve and'all tools constructed in accordancewith the invention may,..therefore, employ a vplateor disc valve of thegeneral typehaving in addition to the two working faces-of the valve, anaxial extension of smaller diameter than the disc, and such a valveisconveniently arranged to be, moved from one beat to another partly bypressure ,built ;up by motionof the piston and partly by drivingfluid-pressure. .70 It is a further object of the invention to .reducein some instances the overall length of a fluid-driven tool of the typedescribed to a min.- imum, sa d, t e fluid i tr bu n m an n ch a toolare .thendisposed in an annular spacebetween the casingef the tool-andan inner rearward extension of-the cylinder, which extension has portsnear its rearward end to allow of cornnu nicationybetween the rearwardend offthe .80 auxiliary valves and-valve casings thereforare in such aconstruction preferably all ofannular form, I V

Subsidiary objects in the various constructional forms of the-inventionare the isolation of the valves from contact with thepiston and the pro-,visionof an arrangement which is easy to asseme nd ono c l n m nufa reY wa a e @1 0 The accompanying, drawings illustrate; by

of example'various forms of pneumatic Figures 1 and laatogetherillustrate a-hammer 'theseverallparts ofj-which are shown, some .out

of position'in order to be in one plane; and, at

979 the parts area section on the line IXIX of 5 .;Figurei.9andat'lO-e-lll are a 'sectionon, the line Figure 3-is alpart'longitudinalsection of an return stroke and accordingly the twofluid-pasalternative 'l n 0f ne ma ham r provision is niade for avoidingexcessive building 'QFigure ei is afpart. longitudinal section of thealternativefqrmQshown in Figure 3' but taken in aidiiferent plane; V v

.Figure 5 is f'alongitudinalsecti n of the valve .110

mechanism showing alternative arrangement of the main valve;

Figure 6 is a longitudinal section of valve mechanism showing a furtheralternative arrangement of the main valve;

Figure 7 shows a pneumatic hammer specially arranged to reduce theoverall length to a minimum while allowing for a long piston stroke;

Figure 8 is a detailed view of the same in that part of the valve boxwith which therauxiliary valve contacts;

Figure 9 is a section on the line 9 -9 of Figure 1, and l Figure 10 is asection on the line 10-10 of Figure 1. v

Referring first to Figures 1 and 2, 1 is the main distribution valve, 2is the auxiliaryvalve in the form of an annular disc, 3 is the piston, 4is the cylinder, 5 the valve box, 6 the auxiliary valve box, 7 thecylinder cover, and 8 the handle which constitutes a casing around thevalve boxes. V

Compressed air enters via port 9 'into recess 10 and (as shown in Figure2) fills ports 11'and 12'and annular recesses 13 and 14. Compressed air'also passes through orifice 15 in the main valve1 into the cavity 16thereof.

Assuming that the components of the hammer are in the position shown inFigure 1 compressed air will now pass between the rear face of the mainvalve 1 and its rear "seat 17 into the annular recess l8 whichcommunicates with the forward end of the piston -3fthrough passages 19,20 and '21, thus driving 'the piston rearwardly, this 'air exhausting toatmosphere through ports 22'and'25 and passages-23 and 24, as theforward end of the piston successively uncovers the ports 22' and 25 011its rearward stroke. During thje rearward stroke of the piston and afterits rear edge covers thefport 25,*'comp'res- 'sion of air in therearward 'or inner end' of the cylinder exerts pressure on the forwardface of the valve 1 by means of the annular groove 26 and ports 27 inthe cylinder cover 7, and this pressure increases. When the forward edgeof the piston uncovers the port 22, the real-face of the main valve 1 isreleased to atmosphere through passage 21 and port 22 so that the built9 :in' the rear end of the cylinder is relieved by means of port 42which is disposed'near the rear up pressure is enabled to force the mainvalve into the position shown in Figure 2.

In this'position compressed'air is now free to enter the rear end'of thecylinder from recess 14 and ports 2'? to 'drive" the piston forward onits striking stroke. -This air exhausts to atmosphere through port 25'and'passages 23 and 24 just prior: to the impact of the piston; 'andowing to this reduction of pressurein the cylinder, the positivepressure on the small end of the main valve 1 forces the main valve onto its forward seating 28 and cuts off the compressed air from the rearend of the cylinder whereupon the cycle again commences. 1

. Turning to the auxiliary valve 2 it will be noted that its rear facecontrols an exhaust port 46 and i a port leading'not only to the forwardend of the cylinder but communicating also through passage '19 withtheports 29 and annular channel 29 on the forward side ofthe auxiliary}valve 2 and also with the annular recess 18 That is to say, both forwardand rear faces ofthe auxiliary valve 2 communicate with the forwardendjof the piston, and also with recess 18 bymeans of the ,ports 29, 30,31, 19, 20 and 21. The area of the forward face of the valve 2 exposedto any presturns fully'o-n its rear stroke.

from the cylinder end) that when compressed air is admitted into recess18 by the main valve 1 and thus into ports 19, 20 and 21, this pressureacts on the forward face of the auxiliary valve 2 and forces it againstits rear seat thus closing ports 30 and 46. However, during the workingstroke of the piston any compression in front of the piston takes theline of least resistance to exhaust and as the passage 19 and port 29together form a more restricted path forthe built up pressure than theport 30, the auxiliary valve 2 is moved forward thus connecting-the port30 with the exhaust port 46. In other words the position and size of theports is such as to ensure that the auxiliary valve 2 moves in adirection opposite to the main valve 1. The port 15 in the small end ofthe main valve 1 and the cavity 16 are of such a diameter that theresultant pressure acting on the end .of valve 1 can be made to controlthe speed of the piston as required. Other methods of securing thissmall positive pressure on the small end of the valve are shown inFigures 5 and 6.

cavity but a small chamber 34 is formed between the end of the valve andthe. mainvalve box'5 whichis fed by a restricted passage 33. In Figure 6a restricted passage 35 in the end of the valve box 5 feeds the cavity36 between the valve 1 and the box and during the forward stroke of thepiston only a leak is allowed into the cylinder by means of a slightlysmaller passage 37 through the main valve. 1

The construction shown'in Figuresl, 2, 5 and 6' applies to all the caseswhere it is; desired that the auxiliary valve shall relieve thecompression set up by thepiston'in the forward endof the cylinder inmuch in excess of the piston.

necessary to relieve .the pressure in'the rear end ofv the: cylinderlatleast during part of the return stroke) so asto ensure that the pistonre- Figures 3. and 4 illustrate analternative arrangement according tothe invention in which the auxiliary valve controls special ports tosecure this result.

Referring to Figures 3 and 4 the compression end of the cylinder (i. e.less than a pistons length This port when. uncovered connects the innerend of the cylinder through passages 41, 40, 31 and 30 to the rear 'faceof the auxiliary valve 2 and thence as before to the exhaust port46shown in Figure 1.

The position of port 42 is such that when the piston does cover it onits rear stroke there will be sufficientcompression set up in thecylinder to reverse the main valve through port'27 and also to reversethe auxiliary valve 2 through passages 39, 38, 43 and 29 and annularchannel 29*. During ithejforward' stroke of the piston the auxiliaryvalve will be firmly held on its rear seating by the incoming compressedair from recesses 14 and.

' 26, port 2'7 and passages 39, 38, 43 and 29, thus keeping the port 30closed during the forward stroke of the piston. The compressed air toreturn the piston on its rear stroke passes from re cesses 13 andlfithrough ports 44, 45 and 21 as shown in Figure 4.- v

Referring to Figures '7' and 8, -1 is the main distributing valve, ,2 isthe auxiliary valve, 3. is the piston, 4 is the cylinder, 5 is the valvebox, 46 is the cylinder cover, 47 is the valve box cover and 8 isthehandle. Air unde'r pressure enters the air port 9 in the'handle8'into chamber 10 and fills'ports '11, 12 and 13 and annular recesses 14and 15. Assuming' the component parts of the tool are as'shown inFigure'l, compressed air will'pass between the forward face of the mainvalve 1 and the valve seating 48 into the annular recess 49 and fromthat recess into port 50 and annular groove 51. The air in this grooveexerts'pressure on the rear face of theauxiliary valve 2 and holds it onits forward seating 52 to close the exhaust ports 53 communicatingbetween this, seating 52 and the exhaust passages 54, 55 in the cylinder4. Air will pass from port 50 into passage 56 by way of passages 57 and58 and through cylinder port 59 forcing the piston on its rearwardstroke. When the front end of the piston has uncovered the main exhaustport 60 the compressed air in the front end of the'cylinder and inpassage 56 andport 50 and recess 49 is exhausted'to atmosphere andconsequently the pressure in ports 11 and the compression developed bythe return of the piston exerting pressure through cylinder ports 61 onthe face of the main valve exposed in thevcavity 62 overcomes'thesmallpositive pressure on the small end of themain valve 1 which has beenholding that valve on its rear seat during the backward stroke of thepiston, and forces the main valve 1 into the'forward position thusclosing the, supply of air into the recess49. Air will now flow throughports 11 across the rear seat of the main valve 1 into the cavity 62 andthence through ports '61 into the rear end of the cylinder, driving thepiston forward on its striking stroke' When the rear end of thepiston'uncovers the main exhaust port 60, the compressed air'which hasbeen driving the piston forward and holding the main valve in itsforward position is exhausted to atmosphere and the positive pressureexerted on the forward end of the valve in recesses 14 and 15 reversesthe main valve, whereupon the cycle again commences. f 1

During the forward or striking stroke of the piston, all compression of.air .on the front of the piston is relieved by means of the auxiliaryvalve 2, because the position of this auxiliary valve is reversed. Thereason for this reversal is that any pressure built up in the'front' ofthe piston acts in the recesses 63. The area of the auxiliary valve 2exposed to this pressure in recesses 63 is slightly less than the areain recess 51 on the opposite side, but as the pressure will take theline of least resistance to exhaust, it will exhaust itself across theforward face of the valve 2 from recesses 63 toexhaust ports 53 whichare open to atmosphere through passages 54 and 55. It will thus be seenthat the piston gives an uncushioned blow up to the moment of impact.

Referring to Figures 9 and 10 it will be seen that the handle portion inwhich the passage 9 is formed is screwthreaded on to the main cylinderand the parts are maintained in adjustment by means of a ring having asplined engagement with the outer surface of the cylinder so as to beaxially movable thereon and having a locking tooth '71 which can enterone or the other of the spaces between teeth '72 formed on the opposedsurface of the handle member according to the angular adjustment of thelatter. The tooth '71 is held in between teeth '72by means of a springring 73 having inturned margins 3 which overh'angshoulders on the handlemember and on the ring 70 respectively. I w I 3 As seen-in'Figure 10 anexhaust air deflector has a spring 81"attached to it by means of rivets82. The spring 80 has its free end formed to engage in a recess such as83 to retain the deflector in position. r

I claim:--' 7 1 1. Fora fluid driven tool of the type describedcomprising a working cylinder," a free piston therein and one or moreexhaust ports to be covered and uncovered by the piston, fluiddistributing means comprising in combination a main valve having twofaces opening to opposite ends of the cylinder, anannular auxiliarybeatvalve and valve casing wherein said auxiliary valve is axially movable,two fluid passages Whichlead from one and the same face of the'auxiliary'valve to' one endof the cylinder and to exhaust respectively, and athird fluid passage leading from the other face of the auxiliary valveto that face of the main valve which also opens to the same end of thecylind r. 2

-2. For a fluid driven tool of the type described comprising a workingcylinder, a free piston therein and one or more exhaust-ports to becovered and uncovered by the piston, fluid distributing meanscomprising' in'combination' a main valve having two faces opening toopposite ends of the cylinder, an annular auxiliary beat valve and valvecasing wherein said auxiliary valve is axially movable, and two fluidpassages which lead from'one and the same face of the auxiliary valve tothe forward end of the cylinder and to exhaust respectively, the firstof which passages is'join'ed. by a third fluid passage having branchedfluid passages leading to the opposite face of the auxiliary valve and:one face of the main valve respectively, v I 1 3. 'For a fluid driventoolof the type described comprising a working cylinder, a free pistontherein and one or more exhaust ports to be covered and uncovered by thepiston, fluid distributing means comprising in combination a 'main valvehaving two faces opening'to opposite ends of the cylinder, an annularauxiliary beat valve "and valve casing wherein said auxiliary valve isaxially movable, two fluid passages which lead from one and the sameface-ofthe auxiliary valve "to the forward end of the cylinder and toexhaust respectively, the first of which passages is joined by a thirdfluid passage having an opening at the opposite face of the auxiliaryvalve of greater cross-sectional area than'that of the opening of thesaid first fluid passage at the auxiliary valve,

and a branchedfluid passage from said third passage leading to onefaceof the main valve.

4. For a fluid driven toolof the type described comprising a workingcylinder, a free piston therein and one or more exhaust ports to becovered and uncovered by the piston, fluid'distributing means comprisingin combination a main valve having two faces opening to opposite ends ofthe cylinder, avalve box wherein an axial extensionof the mainvalveperpendicular to the valve faces is slidably mounted, an auxiliary beatvalve constituted by a flat annular ring mounted coaxially with the mainvalve in' an annular chamber with which the inner and outer peripheralwalls of the ring make a sliding fit, two fluid passages which lead fromone and the same face of the auxiliary valve to one end of the cylinderand to exhaust respectively, and a third fluid passage leading from theother face of the auxiliary passages which 135 tension of the main valve-chamber with which the inner i the length thereof which leads from eredand uncovered by the piston,

ing from the other face opens to the same end of the cylinder.

- 5. For a fluid driven-tool of the type described comprising a workingcylinder, a free piston therein and oneor more exhaust ports to becovered and uncovered by the piston,,fluid distributing means comprisingin combination a main valve having two faces opening to opposite ends ofthe cylinders, anannular auxiliary beat valve and'valve casing whereinsaid auxiliary valve is axially movable,'two fluid passages whichrespectivelylead from one-and the same face of the auxiliary valvegtoexhaust and, to the rearward end of the cylinder at a point in thelength thereof distant from 'the actual rearmost point by a length whichis less than the length of the piston, and a third fluidpassagewhichleads from the other face; of the. auxiliary valveand joins a fluidpassage leading from one face of the main valve to the rearward end ofthe cylinder.

For a fluid driven tool of, the type described comprising a workingcylinder, a free piston therein and one or more exhaust ports to becovered and uncovered by the piston, fluid distributing means comprisingin combination a main valve having two faces opening to opposite ends.of the cylinder, a valve box wherein an axial ex 7 perpendicular to thevalve faces is slidably mouhted, an auxiliary beat valve constituted bya flat annular .ring mounted coaxially with the main valve in an annularand outerperipheral walls of they ring make a sliding fit, two fluid vrespectively lead from one and the same face of the auxiliary valve toexhaust and to the rearward end of the cylinder at'a point I distantfrom the actual rearmost point by a length which is less than the lengthof the piston, and a third fluid passage the otherface of the auxiliaryvalve joins a'fluidp'assage leading from one face of the main valve tothe rearward end of the cylinderi '7. Fora fluid driven toolofthe typedescribed comprising 'a working cylinder a free piston thereinlandoneormore exhaust ports to belcovY- v fluid distributing meansdispos'ed infanannular, space between the casingof the tool and an innerv extension ofthe cylinder andcomprising in combination a main valve having two facesopening to opposite ends of the cylinder, an annular auxiliary beatvalve and valve casing wherein said aux- 'iliary'valveis axiallymovable, two fluid passages,

which lead from one and the same face of the auxiliary valve to one endof the cylinder and to exhaust respectively, a third fluid passageleadof the auxiliary valve to that face of the main valve which alsoopens to thesam'e' end of the cylinder, and ports which are providednear the inner end of said cylinder extension to allow communicationbetween the inner end of the cylinder and the main valve.

8. For a fluid driven tool of the type described comprising a workingcylinder, a free-piston therein and one or'more exhaust ports to becovered and uncovered by the piston, fluid distributing means disposedin an annular space bethe same face of tween the casing of the tool andan inner extension of the cylinder and comprising in combina tion amainvalve having tw faces opening to opposite ends of the cylinder, avalve box where in an axial extensionof the main valve perpendicular tothe valve faces is slidably mounted, an auxiliary beat valve constitutedby a flat annular ring mounted co-axially with the main valve in anannular chamber withwhichthe inner and outer peripheral walls of thering make a sliding fit, two fluidpassageswhich lead from one and thesame face of the auxiliary valve to one end of the cylinder, and toexhaust respectively,fa third fluidpassage leading from the other faceof the auxiliary valve to that face of the main valve which also opensto'the same end of the cylinder, and ports which are provided near theinner end of said cylinder extension to allow communi'cation between theinner end of the cylinder and the main valve.

9. For a fluid driven} tool of the type described comprising a workingcylinder, 2, free piston dicularto the valve faces is slidably mounted,an

annular auxiliary beat valve located on that side of the main valveremotefromthe valve face which opens to the rearward'end of the cylinderand valve casing wherein said auxiliary valve is axially movable, twofluid passages which lead fromlone and the samefaceof the auxiliaryvalve to one end of the cylinderand to exhaust respectively, a thirdfluid passage leading from the other face of the auxiliary valve to thatface of the main valve which also'o'pens'to the same end of thecylinder; and aflui'd passage connecting the fluid supplygline with theend surface of the j extension piece of the main valve. I

10. For a fluiddriven tool "of the type described comprising a working"cylinder, a free piston therein and one or more exhaust ports to be covered and uncovered by thepiston, fluid distributing, means comprising amain valve having two faces opening to opposite ends of the cylinder, a

valve box wherein an axial extensionof themain valve in a directionperpendicular to the valve faces is slidably mounted; an auxiliary beatvalve located onithat' side of the main valve remote from the valve facewhich opens to the rearward end of the cylinder and constituted bya'flat'an- 'nular ring mounted co-axially with the main valve so asto'surround the extension thereof in 'an annular chamber with which theinner and outer peripheral walls of the ring make a sliding fit, twofluid passages which lead from one and the auxiliary valve to one end ofthe cylinder and to exhaust respectively, a thirdfluid passage leadingfrom-the other face of the auxiliary valve to that face of the mainvalve which also opens to the same end of the cylinder, and a fluidpassage connecting the fluid "supply line with the end surface of theextension piece of the main valve.

JOI-IN- ARTHUR.

